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x86: mtrr_cleanup: first 1M may be covered in var mtrrs

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The first 1M is don't care when it comes to the variables MTRRs.
Cover it as WB as a heuristic approximation; this is generally what we
want to minimize the number of registers.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Yinghai Lu 2008-10-04 14:50:32 -07:00 committed by H. Peter Anvin
parent 42fde7a05c
commit 99e1aa17ce
1 changed files with 9 additions and 0 deletions
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9
arch/x86/kernel/cpu/mtrr/main.c
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@ -1293,6 +1293,15 @@ static int __init mtrr_cleanup(unsigned address_bits)
}
nr_range = x86_get_mtrr_mem_range(range, 0, extra_remove_base,
extra_remove_size);
/*
* [0, 1M) should always be coverred by var mtrr with WB
* and fixed mtrrs should take effective before var mtrr for it
*/
nr_range = add_range_with_merge(range, nr_range, 0,
(1ULL<<(20 - PAGE_SHIFT)) - 1);
/* sort the ranges */
sort(range, nr_range, sizeof(struct res_range), cmp_range, NULL);
range_sums = sum_ranges(range, nr_range);
printk(KERN_INFO "total RAM coverred: %ldM\n",
range_sums >> (20 - PAGE_SHIFT));